In the world of the Mario Brothers, Toad lived in a giant mushroom. A mushroom was an unusual place to live once, but mushrooms now have a role in green building design. Houses often include insulators, and styrofoam is a well known insulation material. A new green building material made from mushroom roots uses much less energy than styrofoam or other insulators.

Reuters UK reports that building insulation from a mushroom based material requires less than 2.5 percent of the energy used in styrofoam manufacture. The process uses several plant oils, so it does not require the disposal of toxic waste, unlike other building materials. The company which manufactures this insulation is Ecovative Design.

Greensulate is Ecovative’s green building material. The insulation consists of several other plant waste products such as seed hulls. The filamentous roots of the mushrooms bind these other seed hulls together to create a solid but porous material. Heating the mushroom roots stops further growth and binds the other plant materials together, so this process also doesn’t require any glue. Glue is a major concern in green building design, since many glues release volatile organic compounds which are toxic.

The Greensulate insulation is also fire resistant. The Cornell Mushroom Blog explains how the material becomes fire resistant, since dried mushrooms normally will burn. Rice husks, buckweed hulls, and cottonseed hulls contain lots of silica. The mushroom roots apparently grow by consuming the organic material in these husks, leaving behind the silica. The finished Greensulate also absorbs less water than other building materials.

Greensulate has additional advantages, according to Rensselaer Polytechnic Institute. This mushroom based material requires much less investment than building a factory which can produce styrofoam or other insulators, so it has a cost advantage. Carbon dioxide emissions are not a concern when creating this green building insulation. Mushrooms grow almost anywhere, although the Cornell blog does mention that Ecovative Design uses a specific fungus because of its structural characteristics, such as strength.